Electron source and electron gun

Abstract

The present disclosure provides an electron source, including one or more tips, wherein at least one of the tips comprises one or more fixed emission sites, wherein at least one of the tips includes one or more fixed emission sites, wherein the emission sites includes a reaction product of metal atoms on a surface of the tip with gas molecules.

What is claimed is: 
     
       1. An electron source, comprising:
 one or more tips, 
 wherein at least one of the tips comprises one or more fixed emission sites, and 
 wherein the one or more fixed emission sites comprise a reaction product of metal atoms with gas molecules on a surface of a tip of the one or more tips under an electric field, the emission sites are rooted in the surface of the tip of the one or more tips, wherein the reaction is carried out without an ion bombardment. 
 
     
     
       2. The electron source according to  claim 1 ,
 wherein, at least one of the tips comprises a base and one or more high field strength structures on the base having a higher field strength than that of other portions of the base, and an outer surface of at least one of the high field strength structures comprises metal atoms, and/or 
 wherein at least one of the tips comprises a base and one or more active regions on the base having a larger reaction activity than that of other portions of the base, and an outer surface of at least one of the active regions comprises metal atoms, and/or 
 wherein at least one of the tips comprises a base and one or more high field strength structures on the base having a higher field strength than that of other portions of the base, at least a portion of surfaces of the high field strength structures are active regions having a larger reaction activity than other portions of the surfaces, and outer surfaces of the active regions comprise metal atoms. 
 
     
     
       3. The electron source according to  claim 1 ,
 wherein the electric field is generated by applying a positive bias, a negative bias, or a combination of a positive bias and a negative bias, 
 wherein for applying a positive bias, a strength of the electric field comprises 1 to 50 V/nm, and 
 wherein for applying a negative bias, the strength of the electric field comprises 1 to 30 V/nm. 
 
     
     
       4. The electron source according to  claim 2 , wherein the high field strength structure comprises a protrusion. 
     
     
       5. The electron source according to  claim 4 , wherein the protrusion has a size in an order of sub-nanometers to 100 nanometers. 
     
     
       6. The electron source according to  claim 4 , wherein the protrusion is formed by one or more of the following methods: thermal annealing, application of electric field, thermal-field treatment, etching, or nano-machining. 
     
     
       7. The electron source according to  claim 4 ,
 wherein, for a tip comprising a protrusion, metal atoms on at least a portion of a surface of the protrusion have a same or larger reaction activity than that of other portions of the surface of the base in a reaction with the gas molecules under a vacuum condition, 
 wherein, for a tip comprising no protrusion, the metal atoms on a surface of the active region of the base have larger reaction activity than that of other portions of the surface of the base in a reaction with the gas molecules under a vacuum condition. 
 
     
     
       8. The electron source according to  claim 2 ,
 wherein, the base is made of an electrically conductive material; and/or 
 wherein the high field strength structure is made of an electrically conductive material; and/or 
 wherein the base and/or the high field strength structure have metal atoms on surfaces thereof; and/or 
 wherein the high field strength structure is made of a same or different material from the base; and/or 
 wherein a material of the metal atoms on surfaces of the base and/or the high field strength structure is the same as or different from a material of the high field strength structure, and if the material of the metal atoms on surfaces of the base and the high field strength structure are different, the metal atoms on the surfaces of the base and/or the high field strength structure are formed by an evaporation process or an electroplating process; and/or 
 wherein a material of the metal atoms on surfaces of the base and/or the high field strength structure is the same as or different from a material of the base, and if the material of the metal atoms on surfaces of the base and the high field strength structure are different, the metal atoms on the surfaces of the base and/or the high field strength structure are formed by an evaporation process or an electroplating process. 
 
     
     
       9. The electron source according to  claim 1 ,
 wherein, the gas molecules are introduced gas molecules and/or gas molecules remaining in a vacuum environment, 
 wherein the gas molecules comprise hydrogen-containing gas molecules or a combination of hydrogen-containing gas molecules and one or more kinds of the following gas molecules: nitrogen-containing gas molecules, carbon-containing gas molecules, or oxygen-containing gas molecules. 
 
     
     
       10. The electron source according to  claim 9 , wherein the hydrogen-containing gas molecules comprise hydrogen gas molecules. 
     
     
       11. The electron source according to  claim 8 ,
 wherein, the base comprises an electrically conductive material having a melting point above 1000K, and/or 
 wherein the high field strength structure is made of an electrically conductive material having a melting point above 1000K, and/or 
 wherein a material of the metal atoms on surfaces of the base and/or the high field strength structure is a metal material having a melting point above 1000K, and 
 wherein the reaction product of the metal atoms with the gas molecules comprises a reaction product of metal atoms having a melting point above 1000K with the gas molecules under a vacuum condition. 
 
     
     
       12. The electron source according to  claim 11 , wherein the metal material comprises one or more of the following:
 tungsten, tantalum, niobium, molybdenum, rhenium, hafnium, iridium, osmium, rhodium, ruthenium, platinum, palladium, gold, chromium, vanadium, zirconium, titanium, or metal-hexaboride. 
 
     
     
       13. The electron source according to  claim 12 ,
 wherein the metal material comprises tungsten, and 
 wherein the emission site comprises a hydrogen tungsten compound. 
 
     
     
       14. The electron source according to  claim 2 ,
 wherein, a dimension of an opening angle of an electron beam is adjusted by adjusting a size and shape of the base and/or the high field strength structure of the tip, and/or 
 wherein a number of the fixed emission sites is adjusted by adjusting a size of the high field strength structure and/or the active region, and/or 
 wherein a magnitude or a consistency of voltages at which the electron source emits current is adjusted by adjusting a structure of the base and/or a structure of the high field strength structure, and/or 
 wherein a direction of an emission current is adjusted by adjusting a shape of a top of the tip. 
 
     
     
       15. The electron source according to  claim 14 ,
 wherein, the high field strength structure or the active region having the larger reaction activity is at a central position of a surface of the base, and/or 
 wherein the high field strength structure is on a base having a size greater than a given threshold, and/or 
 wherein the metal atoms are at a top of the high field strength structure or at a central position of a surface of the base. 
 
     
     
       16. The electron source according to  claim 1 , wherein an operation condition of the tip comprises:
 in a case where a temperature of the tip is less than or equal to 1000K, an operation pressure is less than or equal to 10 −3  Pa, or 
 in a case where a temperature of the tip is greater than or equal to 500K, and less than or equal to 800K, an operation pressure is less than or equal to 10 −6  Pa, or 
 in a case where a temperature of the tip is less than or equal to 150K, an operation pressure is less than or equal to 10 −6  Pa. 
 
     
     
       17. An electron gun, comprising:
 the electron source according to  claim 1  for emitting electrons; 
 a cooling device configured for cooling the electron source, wherein the electron source is fixed to the cooling device by an electrically insulating heat conductor; 
 a heating device configured for adjusting a temperature of the electron source; and 
 a gas introduction device configured for introducing a hydrogen-containing gas.